Piston ring expander and rail interlock



NOV. 16, 1954 D w HAMM PISTON RING EXPANDER AND RAIL INTERLOCK FiledFeb. 3, 1953 HUI! FIG3

' III INVENTOR. DOUGLAS w. HAMM PISTON RING EXPANDER AND RAIL INTERLOCKDouglas W. Hamm, Muskegon, Mich'., assignor to Muskegon Piston RingCompany, Muskegon, Mich., a corporation of Michigan Application February3, 1953, Serial No. 334,909

2 Claims. (Cl. 309-43) a greater unit pressure of the outer curvedbearing surfaces of piston rings or ring elements against internalcombustion engine cylinder walls. One place where it has wide use is inconjunction with the steel rail piston ring combination in which, ingeneral, two spaced thin parted steel rails are separated by a spacerand the expander engages against the inner edges of the steel rails topress them outwardly and supplies, in the main, the major portion of thepressure with which the outer edges of the thin steel rails engage thecylinder walls.

Such expander has alternate inwardly extending bowed or curved portionsand outwardly extending humps also curved, the humps bearing against theinner edges of the steel rails and the bowed portions in general beingpressed against the bottom of the piston ring grooves in which located.The outward force acting upon the rails is at spaced apart points in anoutward radial direction.

Such humps of the present expander have merely a pressure contacttherewith. With my invention, an expander of a novel form is providedwhich not only exerts outward pressure on such steel rails but, in ameasure, is interlocked therewith so that relative up and down movementof the rails with reference to the expander is forbidden and, in someforms of pistons, where a piston ring groove may have a rather wideslotted connection with the interior of the piston, the danger of a railchanging position and escaping from the expander is eliminated. Further,with my invention, the number of spaced points at which the expanderengages with and against the steel rails is increased and the distancebetween such points diminished getting a better and more uniformpressure effect.

An understanding of the invention may be had from the followingdescription taken in connection with the accompanying drawing, in which,

Fig. 1 1s a fragmentary perspective view, somewhat enlarged, of aportion of an expander made in accordance with my invention, bearingagainst and interlocked with spaced steel rails.

Fig. 2 is a fragmentary elevation and plan view of one of the outwardlyextending humps of an expander made in accordance with my invention in adifferent form than that shown in Fig. 1, and

Figs. 3 and 4, similarly, are fragmentary elevations and plan viewsthereof of two additional specifically different but equivalent forms ofthe expander at such humps, for attaining the same results.

Like references characters refer to like parts in the different figuresof the drawing.

As is well known in the piston ring art, thin steel rails approximating.020 to .025" in thickness, substantially flat and parted at one side,are used in piston rings spaced from each other as in Fig. l withgenerally a spacer between the rails. With my invention the expander,which is made from thin steel ribbon stock of a width substantiallyequal but slightly less than the axial dimension of a piston ring groovein which installed, has alternate inwardly bowed sections 2 integrallyconnected by outwardly extending curved or bowed humps 3, the expanderhaving oil passing openings in many different forms therethrough forventing one of which forms is shown in Fig. 1.

nited States Patent With my invention, instead of the hump portions 3being of the same width as the remainder of the expander, they arereduced in width preferably by equal amounts at both upper and lowersides a distance approxi mately equal to the thickness of the steelrails 1. The inner edge portions of the steel rails thereupon extendinwardly partly over the humps, bearing against the upper and lowersurfaces 4 at their inner sides, the inner edges coming againstshoulders 5 which are at the ends of the narrowed hump portions 3. Theexpander under stress and deformation when installed in a piston ringgroove will exert an outward pressure transmitted at the shoulders 5 attwo spaced apart points at each of the humps 3 against the rails 1.

The invention which I have made may be embodied in other forms servingthe same purpose and getting the same result, substantially equivalentto that first described and which is shown in Fig. 1. In Fig. 2, at thehumps 3, the metal may be swaged and upset so that the middle portion ofeach hump is reduced in width, as shown at 6, providing upper and lowerflat horizontal surfaces 7. The inner edge portions of the rails Iextend one above the upper surface 7 and the other underneath the lowersurface thereof and, at their inner edges, bear against the shoulders ofthe expander humps back of such surfaces 7 getting substantially thesame action and result as in Fig. 1.

In Fig. 3, a part of the width of the expander at each side and at eachhump 3 is cut away and, also, the metal is split from each end of thecut a short distance making tongues 8 which are bent and curvedinwardly. The intermediate narrowed portion 9 at each hump 3 has upperand lower edge surfaces, similar to that at 4 in Fig. 1, bearing againstthe inner sides of the steel rails one over and the other below suchintermediate portion 9. The inner edges of the rails 1 come against theouter rounded sides of the tongues 8.

In Fig. 4, which shows a still difierent form and one which forpractical manufacturing purposes may be preferred, the ribbon stock fromwhich the expander is made is not of uniform rectangular cross sectionbut has a thickened intermediate portion between its opposite upper andlower edges, with narrowed portions extending above and below suchthickened portion. Such ribbon stock may be formed into the expandershape identically as the present expanders are now made, so that at thehumps 3 the intermediate portions 10 will project outwardly between theupper and lower rails 1, the projecting narrowed portions 11 will extendone upwardly back of the upper rail and the other downwardly back of thelower rail, and serve as stops therefor, similar to the shoulders 5 orthe tongues 8 and identically with the widened portions in Fig. 2 sothat the rails are held securely against any up or down movement withrespect to the expander, engaging against the upper and lower flatsurfaces 12 at the upper and lower edges of the thickened portion of theexpander stock.

The invention has proved very useful and practical in connection withits use with the steel rail expander assembly of piston rings,maintaining the rails in proper position to the expander withoutundesired change of position of one to the other and with a broader baseof bearing of the hump portions of the expander against the inner edgesof the rails.

The invention is defined in the appended claims and is to be consideredcomprehensive of all forms of structure coming within their scope.

I claim:

1. In a generally circular, thin metallic ribbon piston ring expander,having alternate inwardly extending bowed sections and integraloutwardly extending curved humps, the improvement comprising, anintegral outwardly extending band around the outer portions of theexpander of greater thickness than the parts of the expander inwardly ofsaid band, said band at its opposite edges having surfaces in parallelplanes generally perpendicular to the axis of the expander and locatedinwardly from the adjacent edges of the thicker portions of theexpander, substantially equal distances.

2. In a generally circular, thin metallic ribbon piston ring expander,having alternate inwardly extending v 4 btowed sections and integraloutwardblextending humps, References Cited in the file of this patent teimprovement comprising; outwa-r y projecting portions on each humphaving an axial dimension less than UNITED STA-TBS PATENTS the width ofthe remaining portions of the expander, each Number Name Date humphaving opposite, generally parallel surfaces inset 5 2,236,721 TeetorApr. 1, 1941 from the edges ofsaid expander, the thickness at the-pro-2,436,896 Mummert Mar. 2, 1948 jectionsrbei'ng gneater'than thethickness: of the expander FOREIGN PATENTS portions above'and below:said projections.

Number Country Date 10 538,685 Great Britain Aug. 13, 1941

